When World War II threatens to shut down Major League Baseball, candy magnate and Cubs owner Walter Harvey persuades his fellow owners to bankroll a women's league. Ira Lowenstein is put in charge, and Ernie Capadino is sent to recruit players.

Capadino goes to an industrial-league softball game in rural Oregon and likes what he sees in the catcher, Dottie. He offers her a tryout, but she is content working in a dairy and on the family farm while her husband, Bob, fights in the war. However, Dottie relents, as her younger sister (Kit Keller) wishes to try out for the new league. After recruiting other members, the trio arrives at the tryouts at Chicago's Harvey Field. There they meet taxi dancer "All the Way" Mae Mordabito and her best friend, former bouncer Doris Murphy (both tough-talking New Yorkers), soft-spoken right fielder Evelyn Gardner, illiterate and shy left fielder Shirley Baker, and pitcher and former Miss Georgia Ellen Sue Gotlander. They and eight others are selected to form the Rockford Peaches, while 48 others are split among the Racine Belles, Kenosha Comets, and South Bend Blue Sox.

The Peaches are managed by Jimmy Dugan, a former marquee Cubs slugger who initially treats the whole thing as a joke. The league attracts little interest at first. With a Life magazine photographer attending a game, Lowenstein begs the players to do something spectacular. Dottie obliges when a ball is popped up behind home plate, catching it while doing a split. The resulting photograph makes the magazine cover. A publicity campaign draws more people to the ballgames, but the owners remain unconvinced.

As the Peaches establish themselves as the class of the league, Dottie and Kit's sibling rivalry intensifies, which leads to Kit being traded to another team. Prior to a game, the Peaches' utility player, Betty "Spaghetti" Horn, is informed that her husband has been killed in action in the Pacific Theater. The same evening, Dottie's husband Bob appears, having been honorably discharged after being wounded in Italy. The following morning, Jimmy discovers that Dottie is returning to Oregon with Bob. He tells her she will regret her decision.

The team continues without Dottie and makes it to the World Series against Kit's Racine Belles. Dottie unexpectedly rejoins the team for Game 7. After much hard work, the Belles win when Kit scores the final run, after Dottie drops the ball at home plate. The sellout crowd convinces Harvey to give Lowenstein the owners' support. After the game, the sisters reconcile before Dottie leaves to raise a family.

Back to the present (1992), Dottie is reunited with several other players, including Kit, whom she has not seen in several years. The fates of several of the characters are revealed: Jimmy, Bob, and Evelyn have died, while Marla has been married to Nelson, a man she met in a bar, for over 40 years. The original Peaches sing a team song composed by Evelyn and pose for a group photo.

On MLB Network's Costas at the Movies in 2013, director Penny Marshall talked about her initial interest in Demi Moore for the part of Dottie Hinson, saying: "Demi Moore, I liked, but by the time we came around, she was pregnant."[3]

Discussing the skirts they wore playing baseball in the film, Geena Davis said on MLB Network's "Costas at the Movies" in 2013, "Some of our real cast, from sliding into home, had ripped the skin off their legs. It was nutty."[citation needed]

The film was released on July 1, 1992 and was #1 by its second weekend (July 10–12).[4] It was a commercial success, making $107 million in the United States (and an additional $25 million worldwide) on a $40 million budget, and was well received by critics.[5][6][7][8][9]

With 2012 marking the 20th year since the film's release, A League of Their Own was released as a 20th Anniversary Edition Blu-ray on October 16, 2012.[14]

Forty-seven former players of the AAGPBL reunited in New York to celebrate the film and the real women who inspired it. Events included a trip to Cooperstown for a special program at the National Baseball Hall of Fame, reminiscent of the film's final scene depicting members of the AAGPBL and family coming together to witness the honoring of the Women's Professional Baseball League. The reunion wrapped up with a game of softball held at Syracuse's Alliance Bank Stadium.[15]